Question 19M.2.SL.TZ2.a.ii
| Date | May 2019 | Marks available | [Maximum mark: 3] | Reference code | 19M.2.SL.TZ2.a.ii |
| Level | SL | Paper | 2 | Time zone | TZ2 |
| Command term | Explain | Question number | a.ii | Adapted from | N/A |
The table shows the global carbon budget over two decades; the years 1990 to 1999 and 2000 to 2009.
[Source: © International Baccalaureate Organization 2019]
Using the table, explain causes of the changes in carbon flux over the two decades.
[3]
a. increased CO2 flux to the atmosphere due to increased burning of fossil fuels by industry/transportation / cement production ✔
b. «land use change leading to» decreased rate of forest burning
OR
better fire suppression leading to decrease in CO2 release
OR
example of land use changes that uses less fossil fuel
OR
increase in land covered by forests/plants / forests recovering from historical forestry
OR
any other reasonable explanation of land use change that would lead to decreased rate of carbon flow to atmosphere ✔
c. carbon storage in land decreased as less photosynthesis due to fewer forests/more construction
OR
release of methane due to «drying of» wetlands/sealing of land with concrete/buildings/roads ✔
d. carbon storage in ocean increased due to more photosynthesis/algae/greater concentration of CO2 in the atmosphere
OR
increased diffusion/rate of dissolving of CO2 into ocean from the atmosphere
OR
limestone/carbonate accumulation «more snails» ✔
3a(ii) was the question most discussed on the G2 comments. The expectation was that the students would address each of the four arrows, with an explanation for each. Good candidates did this. Others just combined everything into a general essay on climate change. Weaker candidates just restated the figures without any explanation of them at all. Whilst it is appreciated that none of the candidates was around between 1990 and 1999, references to the Industrial revolution were out by well over a century. This question would have benefitted from a larger answer box.
